Kathmandu, April 12 -- On World Health Day on 7 April this week, the Air Quality Index (AQI) in Kathmandu exceeded 300 - one of the dirtiest in any city in the world. Breathing was literally lethal.

Although the main source of pollution this week was smoke from brushfires raging across the country, emissions from diesel and petrol vehicles are a bigger year-round source of hazardous suspended particles and toxic gases.

The good news is that the sale of electric four-wheelers is growing rapidly, and battery-powered vehicles now account for one-third of Nepal's total car imports. Outside Kathmandu, vans, microbuses and three-wheelers are switching to electric as never before

All this has happened even though there is still a hefty tax o...